Hey Aaron, you were spot on with your guess. Renaming the subclass to
noevalexp solves the issue. You rock!!!!!


On 20 September 2013 04:02, Aaron Meurer <[email protected]> wrote:

> I can only guess at what's happening, but does it work if you don't
> name the class "exp"? There is (unfortunately) a global class registry
> in SymPy that uses the name of the class, so a subclass called "exp"
> might inadvertently override exp for other parts of SymPy.
>
> If this is the issue, you can always call the class something like
> UnevaluatedExp, and then put "exp = UnevaluatedExp" at the end of the
> definition for convenience (or always import it as "from module import
> UnevaluatedExp as exp"). The important thing is the __name__ of the
> class.
>
> Of course, we really should get rid of the class registry. But it
> hasn't been done yet.
>
> Aaron Meurer
>
> On Wed, Sep 18, 2013 at 11:51 PM, Ben Lucato <[email protected]> wrote:
> > I know this is looking back a month or two, but I have just started to
> use
> > your idea about subclassing.
> >
> > However, it is having unintended side effects.
> >
> > Including the code:
> >
> > class exp(sympy.exp):
> >     @classmethod
> >     def eval(cls, arg):
> >         return
> >
> > in a module like noevals.py, and then subsequently importing noevals has
> > disabled eval in the regular sympy.exp. I am super new to subclassing in
> > general, but I know it's this code because when I delete these 4 lines
> the
> > problem goes away. How do I retain this subclass without altering the
> > parent's behaviour?
> >
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-- 


Ben Lucato
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